Group Info

Other manufacturers will allow some defects in the contact zone 1. And some,
the ones you should avoid, do not have a standard in Fiber
Optic Splice Closure . Important point: Zero defects in this area
are achievable and you should ask for it.

A fiber optic cable tester is a hand-held troubleshooting device that sends
red light from a semiconductor laser (635nm) down a fiber to check for faults
such as cracked fibers or defective splices.

The visible red light travels along the fiber core until it reaches a fault,
where it leaks out of the fiber. Light leaking through the fault can be seen
through plastic coatings and jackets under suitable illumination. Infrared light
in the signal leaks out at the same point, but your eyes cannot see it. The
tester emits Class II red laser beam, making the light escaping from the damaged
fiber easily visible from a distance.

Attenuation of glass fibres is much higher at 630 to 670nm wavelengths of red
light than in the 1300 to 1650nm transmission window, but the red light can
still travel up to 5km through standard fibers. Note that the fibers must be
exposed to use fiber optic cable tester effectively. If the red light leaks out
inside a thick cable wrapped in black plastic, you can't see it.

This technique is particularly valuable in DOME
Fiber Closure bays and other places inside buildings where fibres
are exposed.